Clark Island Sea Lion Likely Has Brain Damage From Toxin
By Cat Sieh, The Bellingham Herald, Wash.
Aug. 5–A California Sea Lion that hauled itself onto a Ferndale family’s boat off Clark Island Sunday, Aug. 3, is likely suffering the poisoning effects of a toxin found in algae, marine mammal rescuers say.
The sea lion, a 2- or 3-year-old female, has shown unusual and erratic behavior, a red flag for domoic acid poisoning, said Amy Traxler, coordinator at the San Juan County Marine Mammal Stranding Network in Friday Harbor.
Domoic acid is a neurotoxin that occurs naturally in algae. Marine mammals affected by the toxin can display erratic, aggressive behavior and often become disoriented, said Mieke Eerkens, spokeswoman for Marine Mammal Center in Sausalito, Calif., where toxic algae blooms are more common.
Domoic acid, which can be lethal in marine mammals, affects the part of the animal’s brain that manages navigation skills, Eerkens said. Many affected animals will show up in areas out of their usual range. Traxler said male sea lions frequent the San Juan Island area, but it’s unusual for a female to appear in that range.
“Often when there’s a sea lion where it normally wouldn’t be, we’d suspect (algae poisoning),” Eerkens said.
Traxler said the same sea lion in May opened her mouth and charged at a woman, her young son and their dog on Jacksons Beach, near Friday Harbor. The sea lion was identified as the same one through photographs showing puncture-like marks on her neck.
Animals suffering algae poisoning often have full body seizures and smaller brain seizures, Eerkens said. There are two types of poisoning, acute and chronic. An animal with acute poisoning can often be treated for seizures and released back into the wild, Eerkens said, though there is little research about these animals’ long-term survival.
Animals with chronic poisoning often have permanent brain damage or atrophy, Eerkens said.
Based on the behavior of the sea lion spotted Sunday, Eerkens said the animal likely has brain damage.
Traxler said the Marine Mammal Stranding Network is interested in tracking the sea lion and encourages anyone who sees it to call the network at (800) 562-8832.
If the animal appears on a beach frequented by people, Traxler said the network would capture her, perform medical tests to better understand her condition and possibly tag her for further tracking.
A 2007 study by The Royal Society argues that an increase in toxic algae blooms off the California coast has caused chronic health effects in California Sea Lions, and that those effects have increased dramatically in the past decade.
Possible explanations for increased toxic algae blooms listed in the 2007 study include overfishing, discharge of ballast waste, an increase in chemical nutrients and global climate change.
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